AEROMAGNETIC SURVEY. Miyake-jima carried out in 2011,2012, 2013 are presented in this report.

Transcription

1 AEROMAGNETIC SURVEY This is a continuation of the report of aeromagnetic surveys by the Hydrographic and Oceanographic Department. The results of three surveys, Izu-Torishima, Nishinoshima and Miyake-jima carried out in 2011,2012, 2013 are presented in this report. Key word: aeromagnetic survey. 1. Survey The aircraft used for the survey was MA725(DHC-8). The aircraft was equipped with a tail-stinger of non-magnetic plastics of 1.5 meters long at the rear of the fuselage. The instruments used for the survey are a optical pumping magnetometer and GPS receiver. The optical pumping magnetometer measured geomagnetic total intensity sampling rate 20Hz with an accuracy of 0.01nT. 2. Data processing and results The measured total intensity include components of external field variation. The correction of the external field variation was carried out based on the continuous magnetic observations at a reference magnetic observatory close to the survey area. For calculations of magnetic anomaly, the IGRF2010 was used as the core field model in accordance with the recommendation of the IAGA. The details on the compiled aeromagnetic surveys are listed in Table 1. Fig. 1~3 show the magnetic anomaly of the total intensity. Reduction and compilation of this report have been made by K.Ogata,K.Onodera and K.Koyama belong to Geodesy and Geophysics Office. Reference Data Report of Hydrographic Observations, Series of Astronomy and Geodesy, No.31, 1997, Data Report of Hydrographic Observations, Series of Astronomy and Geodesy, No.32, 1998, Data Report of Hydrographic Observations, Series of Astronomy and Geodesy, No.33, 1999, Data Report of Hydrographic Observations, Series of Astronomy and Geodesy, No.35, 2001, Data Report of Hydrographic Observations, Series of Astronomy and Geodesy, No.36, 2002, Data Report of Hydrographic Observations, Series of Astronomy and Geodesy, No.37, 2003 Data Report of Hydrographic Observations, Series of Astronomy and Geodesy, No.38, 2004 AEROMAGNETIC SURVEY( ) AEROMAGNETIC SURVEY( )

2 Table 1. Details on the compiled aeromagnetic surveys Cruise index 11TORI 12NISI Area Izu-Torishima Nishinoshima Period Nov. 15, Aug Aircraft MA725 MA725 Flight Altitude 710m 310 m Magnetometer ABOP-35(Opticalpumped ABOP-35(Opticalpumped Potassiumom Magnetometer) Potassiumom Magnetometer) Positioning GPS GPS Track lines 0.5 naut. Mile N-S 0.5~1 naut. Mile N-S Anomaly map Fig. 1 Fig. 2 Scale of original map 1/100,000 1/100,000 Map projection TM TM Reference Magnetic Observatory Kanoya ( N, E) Chichijima (27 06.'0 N, '8E) Reference value for an 46,421 nt 41,120 nt External field correction Core field model IGRF2010 IGRF2010 Contour interval 50nT 50nT Epoch year Cruise index 13MI Area Miyake-jima Period Jun Aircraft MA725 Flight Altitude 1,525m Magnetometer ABOP-35(Opticalpumped Potassiumom Magnetometer) Positioning GPS Track lines 0.25 naut. Mile N-S Anomaly map Fig. 3 Scale of original map 1/50,000 Map projection TM Reference Magnetic Observatory Kakioka (36 13.'9 N, '2 E) Reference value for an 46,555 nt External field correction Core field model IGRF2010 Contour interval 25nT Epoch year

3 ; > 0 ; < 0 - -;=0 Kozu-shima contour interval:50nt Fig.1 Geomagnetic total intensity anomaly map in and around Izu-Torishima. (Land area based on material Geographical Survey Institute)

4 contour interval 50nT Fig.2 Geomagnetic total intensity anomaly map in and around Nishinoshima.

5 contour interval 25nT Fig.3 Geomagnetic total intensity anomaly map in and around Miyake-jima. (Land area based on material Geographical Survey Institute)